Methods for making fasteners

ABSTRACT

A method for forming a fasteners is disclosed comprising providing a multiplicity of suitable polymer particles, providing a base with a front surface, and dispersing the particles onto at least one discrete area of the contact release surface, forming a predetermined shape. The dispersed particles are provided in a semiliquid state of a suitable viscosity, at least some of the particles in the discrete areas being in contact with the contact release surface for a time sufficient to transform into preform projections. The method further comprises conducting and fixing the front surface of the base with the terminal ends of at least some of the preform projections and removing the base from the contact release surface to separate the preform projections fixed thereto and form engaging projections projecting from the front surface of the base in the form of a predetermined shape.

TECHNICAL FIELD

The present invention relates to methods of manufacturing fasteners,particularly male components for fasteners of the touch-and-close type,also known as hook-and-loop type fasteners.

BACKGROUND OF THE INVENTION

It is common to use certain types of hook-and-loop type mechanicalfasteners for fixing disposable diapers, training pants and incontinencegarments around a wearer. One approach is a thin, molded male fastenerwith low loft loop materials, preferably nonwoven, fabrics as the femalecomponents. For these uses generally low cost, soft touch, appropriatestrength and increasing stretch in the waistline are important.

Hooks can be directly molded as disclosed for example in U.S. Pat. No.5,315,740, assigned to Velcro, which discloses molded hooks with lowdisplacement volumes so that it needs only to displace a small volume ofloop fabric in order to engage therewith. The patent discloses are-entrant hook, i.e., whose tip-portion curves over and down toward thebase sheet from the upper end of the hook to define a fiber-retainingrecess on the underside of the hook.

It is also known to cap molded stems on webs. Mushroom-shaped engagingprojections obtained by this process are disclosed in U.S. Pat. No.5,679,302 and U.S. Pat. No. 5,879,604 in which an extruded polymer layeris pressed against a mold with mold cavities, the cavities producingprojecting stems, integral with the base. The terminal ends of the stemsare then deformed with a heated pressure roller, forming the loopengaging projections. U.S. Pat. No. 6,054,091 discloses a similar methodin which, however, the heated deforming surface gives an essentiallylateral deformation to the stems during the deformation thereby formingre-entrant, J-shaped hooks with flat top portions. The solution of U.S.Pat. No. 6,627,133 differs from the previous ones in that the stemmedweb, to be capped with a heated pressure roller, is manufactured withthe method of U.S. Pat. No. 6,287,665, i.e., with a special moldconstituted by a cylindrical printing screen. All documents mentioned inthis paragraph are similar in that they flatten preformed stems by a hotroll.

US Patent Application 2004/0031130A1 discloses a method in which aproduct, comprising a polymer base and stems integral with andprojecting from a base is extrusion-molded with a mold roll having amultiplicity of sophisticated mold cavities. The distal ends of thestems are then heated and melted while their feet are kept cold andsolid. The melted ends are then flattened with a deforming surface. Thesame approach, i.e., pre-heating and successively flattening stems,appears in U.S. Pat. No. 6,592,800, U.S. Pat. No. 6,248,276 and U.S.Pat. No. 6,708,378, the latter ones also disclosing capping with a roughcontact surface, creating roughened flat tops of engaging projections.

U.S. Pat. No. 6,039,911 discloses a stem-deforming apparatus comprisinga long variable nip, e.g., a pair of co-operating conveyors, whichgradually compressively deform the stems, unitary with the base.

U.S. Pat. No. 6,470,540 uses a hot extruded layer for deforming stems,which results in semi-spherical mushroom heads.

In U.S. Pat. No. 3,550,837 a male fastener member is described whoseeach engaging projection is constituted by an irregularly shaped granulewith a special multifaceted surface, adhesively adhered to the base. Thefastener is suitable for securing a flap of a disposable carton againstopening. Engaging is provided by the granules comprising a number oftiny flat planes forming a multifaceted surface.

In U.S. Pat. No. 3,922,455 nibs of various shapes are grafted ontolinear filaments, the linear filaments, protruding from a base, formingthe engaging elements of a male fastener component.

In PCT publication WO 01/33989, particles are, with a scatter head of ascatter coater, randomly scattered, and fixed, onto a base. Eachengaging projection is constituted by several agglomerated particles,though some individual particles may also be left present.

It was therefore an object of the present invention to provide low-costmale mechanical fasteners with advantageous properties. It was anotherobject of the present invention to provide commercially attractivealternatives to the mechanical male fastener systems available so farand methods for making them.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a hook fastener capable of engaging asuitable loop fabric comprising a base with a front surface and a backsurface, where at least one surface has a multiplicity of engagingprojections having a top surface and an attached end. The attached endis fixed to the surface of the base where a plurality of saidprojections are arranged in a region to form one or more shapes.

In a preferred method polymer particles are dispersed onto a contactrelease surface using electrostatic attraction to impact the particlesonto the contact release surface.

In more detail the present invention provides a fastener for engagingwith a loop fabric comprising a base with a front surface and a backsurface, where at least one surface has a multiplicity of engagingprojections having a top surface and an attached end, which attached endis fused to the surface of the base where a plurality of saidprojections are arranged to form one or more shapes. (Thereafter herein,the engaging projections are referred to as being attached to the“front” surface of the base. This is done for purposes of illustrationand encompasses attachment of engaging projections to either surface).The engaging projections are arranged in a nonuniform distribution in aregion so as to collectively form one or more predetermined shapes onthe base. These shapes are preferably discrete and can create functionalhook regions adjacent nonfunctional or lower functional hook containingregions. The shapes can be determined by functional or artisticconsiderations and can extend continuously along a dimension of the baseor be discrete islands within a front or back surface of the base.Preferably the at least some engaging projections top surface ends forman edge angle surrounding the projections, with a mantle surfaceextending from the top surface edge to the attached end; at least onecontour line of a side view of the mantle surface being strictly convexfrom a top surface edge to the attached end.

The present invention furthermore provides a fastener, as describedabove, for engaging with a loop fabric, comprising a base having a frontsurface with a multiplicity of engaging projections at least some of theengaging projections having a top surface end and an attached end. Theengaging projections attached ends are fixed or preferably fused to thefront surface of the base and the top surface forming an edge at leastpartially surrounding the projection.

The present invention also provides a first subset method for forming afastener comprising:

providing a multiplicity of suitable polymer particles;

providing a base with a front surface;

dispersing onto a contact release surface a multiplicity of polymersparticles in at least one discrete area of the contact release surfaceforming a predetermined shape;

providing the polymer particles, dispersed on the contact releasesurface, in a semiliquid state of a suitable viscosity, at least some ofthe particles in the discrete regions or areas being in contact with thecontact release surface for a time sufficient to transform into preformprojections;

conducting and fixing the front surface of the base with the terminalends of at least some of the preform projections;

removing the base from the contact release surface thereby separatingthe preform projections fixed thereto,

thereby forming engaging projections projecting from the front surfaceof the base in the form of a predetermined shape.

The polymer particles are generally dispersed into a predetermined shapeas preform projections by use of a masking surface where particlesimpact the masking surface and those particles passing though themasking surface forming the predetermine shapes. The polymer particlescan be impacted onto the masking surface by gravity, electrostaticattraction, impaction or other suitable forces or any combinationthereof. The preform projections on the contact release surface are thentransferred to the base, retaining approximately the same predeterminedshape, so as to form engaging projections approximately of thepredetermined shape.

In a preferred method polymer particles are dispersed onto a contactrelease surface using electrostatic attraction to impact the particlesonto the contact release surface.

-   -   The present invention also provides a second subset method for        forming a fastener comprising:        -   providing a multiplicity of suitable polymer particles;        -   providing a base with a front surface;        -   dispersing onto a contact release surface a multiplicity of            polymers particles;        -   providing the polymer particles, dispersed on the contact            release surface, in a semiliquid state of a suitable            viscosity, at least some of the particles in discrete            regions or areas being in contact with the contact release            surface for a time sufficient to transform into preform            projections;        -   conducting and fixing the front surface of the base with the            terminal ends of at least some of the preform projections in            a predetermined region or area of the base;        -   removing the base from the contact release surface thereby            separating the preform projections fixed thereto,            thereby forming engaging projections projecting from the            front surface of the base in the form of a predetermined            shape.

The polymer particles can be selectively adhered in these predeterminedregions or areas by providing for preferential adhesion to the base inthese predetermined areas. Preferential adhesion could be accomplishedby providing areas with adhesion promoting layers or treatments, orproviding areas with adhesion deterring layers or treatments, includinga removable mask. It is also possible to combine the two methods; thatis by depositing the particles onto the contact release surface in apredetermined area, thereafter transferring the particles onto the basein a predetermined area with preferential adhesion to the particles.

The present invention also encompasses the use of adhesives in variousmethods and configurations. Such adhesives can include any of the widevariety of adhesives (hot melt, UV cure, etc.) that are known in theart, but preferably include pressure sensitive adhesives, as describedherein and referred to hereafter by the term PSAs. A PSA can be providedon the base front surface for example in discrete areas adjacent to thepredetermined regions of engaging projections described above or on thebase back surface or both.

The male mechanical fasteners of the invention can also be used indisposable diapers. In a preferred embodiment the fastener is capable ofengaging with the nonwoven outer shell of a diaper strongly enough tosecurely keep the soiled diaper in a folded state. Further, preferablythe engagement with the nonwoven outer shell of a diaper is strongenough to secure the diaper around a wearer during use, thereby making aseparate frontal tape, of a special loop fabric, in the landing zoneunnecessary, which can provide considerable cost saving.

The male mechanical fasteners of the present invention can also be usedto form a so-called back-to-back wrapping tape that has the fastener ofthe present invention on one face thereof thereby offering such newpossibilities, deriving from the invention, such as an inexpensive,highly flexible still strong, very thin or easily cut wrapping tape. Ina preferred embodiment, the wrapping tape can be easily written uponwith a pen. In another preferred embodiment the wrapping tape may beelastically stretchable and can be advantageously used for packaging ortechnical (e.g. cable wrap) applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic side view of the apparatus for manufacturing afastener of the invention.

FIG. 1 b is a segmented top view of a masking surface used in theapparatus of FIG. 1 a.

FIG. 1 c is an enlarged cross sectional view of the fastener of FIG. 1a.

FIG. 2 a is a schematic side view of a second apparatus formanufacturing a fastener of the invention.

FIG. 2 b is a segmented top view of a masking surface used in theapparatus of FIG. 2 a.

FIG. 3 a is a schematic side view of a third apparatus for manufacturinga fastener of the invention.

FIG. 3 b is a segmented top view of a first masking surface used in theapparatus of FIG. 3 a.

FIG. 3 c is a segmented top view of a second masking surface used in theapparatus of FIG. 3 a.

FIG. 4 a is a schematic side view of a fourth apparatus formanufacturing a fastener of the invention.

FIG. 4 b is a segmented top view of a masking surface used in theapparatus of FIG. 4 a.

FIG. 5 a is a schematic side view of a fifth apparatus for manufacturinga fastener of the invention.

FIG. 5 b is segmented top view of a patterned electrode belt used in theapparatus of FIG. 5 a.

FIG. 6 a is a schematic side view of a sixth apparatus for manufacturinga fastener of the invention.

FIG. 6 b is a segmented top view of a base film with regions ofpreferential adhesion used in the apparatus of FIG. 6 a.

FIG. 7 a is a schematic side view of a seventh apparatus formanufacturing a fastener of the invention.

FIG. 7 b is a segmented top view of a masking surface used in theapparatus of FIG. 7 a.

FIGS. 8 a-8 d are segmented top views of alternative shapes possibleusing methods of the invention.

FIGS. 9 a and 9 b are segmented top views of alternative design shapespossible using methods of the invention.

FIG. 10 is a segmented top view of a fastener possible using methods ofthe invention having adhesive areas adjacent hook containing regions.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a fastener for engaging with a loopfabric. The fastener comprises a base having a front surface with amultiplicity of engaging projections arranged into predeterminedpatterns or shapes formed by a multitude of the engaging projections.Namely a plurality of engaging projections together create a shape on abase based on their size and/or density being different than in adjacentareas of the base, the shape is one that is generally clearly visible tothe naked eye. As shown in FIG. 1 c, at least some of the engagingprojections 13 have a top surface end 14, where at least some engagingprojections top surface ends 14 form an edge angle 18 surrounding theprojections 13. Opposite the top surface end 14 is an attached end 16,which is attached to the front surface 20 of the base 4. There can be amantle surface 17 extending from the top surface 14 edge 15 to theattached end 16. The mantle surface 17 in some embodiments has at leastone contour line of a side view of the mantle surface 17 that isstrictly convex from a top surface edge 15 to the attached end 16, asshown in FIG. 1 c.

The present invention furthermore provides a fastener for engaging witha loop fabric, comprising a base 4 having a front surface 20 with amultiplicity of engaging projections 13 arranged in to predeterminedpatterns or shapes at least some of the engaging projections having atop surface end 14 and an attached end 16, which attached end 16 isfixed or fused to the front surface 20 of the base 4 and the top surface14 forming an edge 15 at least partially surrounding the projection 13.

The hook fastener can have plurality of engaging projections form adiscrete or continuous shape. Shape is defined as a plurality of theengaging projections that are organized into a specific area or region,where there are more or less, or different types or sizes, of engagingprojections outside this region. A shape does not need to have definededges but rather could have a gradual change in the density ordistribution of the engaging projections from, e.g., a high densityengaging projection area to an adjacent low density engaging projectionarea. This low density engaging projection area could have little or nohook engaging projections. Preferably the shape is formed by theplurality of engaging projections in a region having a relatively highdensity of engaging projections. The plurality of engaging projectionsforming a shape can extend substantially continuously in one dimensionof the base as shown in FIG. 8 a. The shapes in most embodiments willhave a minimum width dimension less than the width of the base as itshould not cover the entire surface of the base The shapes could besurrounded by secondary areas having a either a different type and/ordensity of engaging projections. In a preferred embodiment the shapesare relatively high density regions having an average density ofengaging projection of at least 1 gram per square meter (gsm) ofparticles, or at least 2 gsm of particles which are of a general averagesize of about 50 to 1000 microns or generally 50 to 500 microns. (Notethat the engaging projection average size, and density of the engagingprojection material, can be used to convert this measurement to thenumber of engaging projections per area). In another alternative thesecondary regions have an average density of engaging projections ofless than about 50 percent of the average density of engagingprojections in the shape region, or less than about 25 percent of theaverage density of engaging projections in the shape region. In apreferred embodiment at least one region will have little or no engagingprojections. For those shapes that extend continuously in one dimensionof the base the shapes generally will have a minimum width dimensionless than the width of the base. The shapes generally would have aminimum width dimension of greater than 1 mm or greater than 4 mm.

The shaped regions of engaging projections may be provided on a baselayer that is a continuous web. The regions of engaging projections canbe present as a plurality of regions on the surface of the continuousweb, for example in a repeating or nonrepeating pattern of regionsbearing engaging projections, partially or completely surrounded byregions lacking any engaging projections (or, as discussed herein,bearing engaging projections that are present at a lower density, orthat differ in some property such as size, height, color, aspect ratio,etc.). Various potential shapes that engaging projection regions 77 mayform on a base film 4 are illustrated in FIGS. 8 a-8 d. The shapedregions bearing engaging projections may be present as discrete regionswithin a contiguous area that has no engaging projections (or, that havediffering engaging projections as discussed above); or, the engagingprojections may be present in a contiguous area that has regions of no(or fewer, or different) engaging projections interspersed therein.

The engaging projection regions or areas can serve a wide variety offunctions. The basic premise is that of providing one or more sets ofengaging projections only in the regions in which they are desired to bepresent on the substrate (base). Such regions of engaging projectionsmay provide benefits in terms of adhesion, cost, ornamental or visualeffect, or some other factor. A example is the placement of a hookcontaining region (strip, rectangle, or shape as desired) on an articlein a predetermined desired location. This is customarily done by makinga uniform hook material on a backing, such as a film, and cuttingdiscrete pieces of this hook material and bonding it to the articlewhere fastening functionality is desired (for example onto a sheet ofmaterial that is to be used as a diaper side panel, ear, or backsheet).This is typically done by use of adhesives or melt bonding. The currentmethod allows regions of engaging projections to be formed directly onthe desired article in the size and location desired. For example,engaging projections may be placed in desired regions on a continuousweb, intended to be used as a diaper side panel, ear or backsheet, etc.from which individual pieces bearing the engaging projections may thenbe taken (for example by die-cutting), to form a diaper side panel, earor backsheet, etc.

It is also possible to provide the regions of engaging projections so asto impart unique or novel mechanical performance. For example, theengaging projections can be present in the form of regions (for example,strips), separated by regions without engaging projections, or with alower density (that is, the number of engaging projections per unit areaof the base film), of engaging projections, or with larger or smallerengaging projections, etc. Such configurations may provide enhanced ortailored properties, for example in peel or shear behavior. For example,regions of low shear or peel properties can be interposed with regionsof high shear or peel properties, which might serve to provide moreuniform performance when a fastener is disengaged from a loop substrate.Or, a region with a lower density of engaging projections (which, again,includes regions of no engaging projections) may serve as a fingerliftzone, for example in use as a diaper closure. If engaging projectionsare applied in regions in a multistep process the regions can overlap inwhole or in part which can result in a certain number of “stacked”projections resulting from the deposition of preform projections ontoexisting preform projections. The presence and amount of stackedprojections can also be tailored to achieve desired engagementproperties.

The engaging projection regions can also be provided so as to impartnovel and unique visual or ornamental effects. The engaging projectionscan be provided in a region that is shaped so as to form a recognizableimage or shape, e.g. an object, a letter, or the like, as exemplified inFIG. 9 a. Multiple shapes could be provided to create a more compleximage or shape or be repeated in simple patterns. These visual effectscan be augmented by providing the engaging projections in one or morecolors (via use of pigmented materials, etc.), or by the use ofreflective additives, and so on.

One alternative embodiment of providing unique visual or ornamentaleffects is to provide the engaging projections on a base that haspreprinted graphic elements. (The preprinted graphic elements can bepresent on the top surface or bottom surface of the base layer,depending on whether or not the base layer is transparent.). The regionof engaging projections could be used as a graphic element inconjunction with the preprinted graphic elements. For example, the baselayer can be preprinted with a visual image or scene (e.g. a garden),and the region of the engaging projections can then be deposited in theshape of a flower. The shaped engaging element region may be placed atrandom in the preprinted visual image. Or the shaped engaging elementregion may be placed into a predetermined location in the preprintedvisual image, as shown for example in FIG. 9 b, in which a shapedengaging projection region 77 is placed in a preprinted visual image 78on a base film 4. The engaging projections can also be provided so as tocomprise a background in a predetermined region (for example, theengaging projections could appear to be individual snowflakes in alandscape scene).

The engaging projections are provided by means of depositing preformprojections onto a surface of a preprinted base. The preform projectionsmay be deposited in areas, which are not imaged (i.e. do not bear ink,pigment, metalized coating, etc). Alternatively the preform projectionscan be deposited onto imaged areas as long as the imaging layer is suchthat the preform projection can be bonded satisfactorily to it. Or, ifthe imaging layer is sufficiently thin, it may be possible to fuse thepreform projection to the underlying base front surface, through theimaging layer, by deforming, melting, or otherwise displacing theimaging layer.

As mentioned, the polymer particles used to form the engagingprojections can be colored, tinted, pigmented, etc., for specific visualpurposes. Multiple regions can be provided with different color engagingprojections, or different densities or sizes of engaging projections,for specific visual effects.

The present invention also encompasses the use of adhesives, preferablypressure sensitive adhesives (PSAs). Such PSAs include a wide variety ofmaterials known in the art, for example, natural rubber adhesives, blockcopolymer-based PSA's (for example, those based on elastomers availablefrom Kraton Polymers, of Houston Tex.), acrylate-based PSA's, andsilicone-based PSA's. PSA's may be chosen so as to bond well topolyolefinic thermoplastic materials (e.g. polypropylene, polyethylene,and copolymers and blends of the same), and might include, for example,the family of PSAs available from 3M Company under the designation LSE(e.g., LSE 300). Other suitable compositions may be based onsilicone-polyurea based pressure sensitive adhesives. Such compositionsare described in U.S. Pat. No. 5,461,134 and U.S. Pat. No. 6,007,914,for example.

In one embodiment, the PSA may be provided in an area adjacent theregion bearing engaging projections. Either or both the PSA and engagingprojection regions may be present as discrete or continuous regions. Forexample, in FIG. 10 is pictured downweb stripes 91 of PSA adjacent todownweb stripes 92 of engaging projections.

The base used in the methods of the invention can be any suitablecontinuous or discontinuous base web such as a porous or nonporouspolymer film, a laminate film, a non-woven web, a paper web, a metalfilms and foils or the like. The base could be modified by any knownmethod such as by being printed, embossed, flame treated, laminated,particle coated, colored, or the like. A polymer film used as a base canbe oriented or unoriented. In conjunction with the methods describedlater, the base film can be provided such that it possesses areas thatvary in the ability to bond to the preform projection, which is yetanother way of providing a substrate with engaging projection regionspresent in discrete shapes, patterns, and the like. The base filmsurface can be smooth, or can be provided with features such asprojections or valleys molded into the base which could be used asripstops, tear propagation lines or other features, which could be onthe front or rear face of the base.

The surface of the base can also be roughened, for example withparticles previously scattered and fixed thereon. The particles shouldbe brought and fixed on the base 4 in a way that at least the terminalends of the projections can be formed from the particles. Projectionscan consist completely of the particles without any further modificationof said particles. For bringing and fixing the particles to the (smoothor roughened) front surface, several methods are taught, e.g., randomscattering and adhering, for example, in the cited PCT publication WO01133989, the entire disclosure of which is hereby incorporated byreference.

The word “particle”, as used herein, refers to a solid, liquid orsemi-liquid particle, including, for example, granules, pellets, powdersand droplets. Appropriate particles can be selected based on thediscussions herein. If the embodiment of this invention relying onelectrostatic deposition of particles (as described later herein) isused, the particles should be chosen so as to be compatible with thisprocess. In electrostatic deposition, particles are moved under theinfluence of an electric field so as to impinge on the base (whetheronto selected regions or uniformly onto all regions of the base). Thus,in this instance the particles must be susceptible to having an electriccharge imparted to them (otherwise they would not move under theinfluence of the electric field). Such methods are well known in the artand the selection of such particles is straightforward.

In terms of the properties of the engaging projections that are formedfrom the particles, it is preferable if at least some engagingprojections are provided with a side view which strictly tapers from thetop surface or top surface edge to the attached end at the front surfaceof the base. As used herein, a side view means a view takenperpendicular to the front surface of the base. Strictly tapering meansthat the nearer the engaging projection gets to the base, the narrowerthe projection becomes. For example, a cylinder is not a strictlytapering shape. This type of tapering will pull engaged fibers down tothe front surface of the base when a shear load is applied to thefastener without the fibers being caught at a nontapered portiondisplaced from the front surface of the base. Thus the torque on theengaging projection is minimal so the base can be weaker, i.e., can becheaper, more flexible, more skin friendly, thinner etc. Furthermore,the fastener may have a relatively large surface area formed by theprojection tops, making the fastener smooth to the touch, while alsohaving a relatively low total surface area of the projection attachedends connected to the base, increasing the flexibility andskin-friendliness of the fastener. The engaging projections can also becharacterized by a ratio of the perimeter of area of the engaging top tothe height of the engaging projection, which is generally 1.1 to 50, andis preferably 1.2 to 20. The engaging projection also generally forms anoverhanging rim, which generally is the difference between the topsurface area and the area of the attached end.

Turning from the materials used to the methods of the invention, apreferred general set of methods for manufacturing a male fastenercomponent with predetermined shapes of engaging projections inaccordance with the invention generally comprises the basic steps of:

providing a base with a front surface;

providing particles of polymer material;

providing a contact release surface of a suitable surface energy;

dispersing, on the contact release surface, a multiplicity of thepolymer particles;

bringing or providing the polymer particles into an at least semi-liquidor softened state of a suitable viscosity, providing preform projections(preform projection signifies a projection that to at least some extenthas been preformed into the shape of the final engaging projection)sitting on and projecting from the release surface. The preformprojections along their edges contacting the contact release surfacewill form contact angles, which contact angle is influenced by thesurface energies of the polymer particles and the contact releasesurface. The polymer particles are maintained in a semiliquid state fora suitable period of time so that they form an acute contact angle;

the preform projections can then be at least partially solidified forcontacting and fixing to the front surface of the base with the terminalends of at least some of preform projections, while essentiallymaintaining the shape of the edge formed by the contact release surface;

the preform projections are then further solidified sufficient toseparate and remove the preform projections from the contact releasesurface thereby forming engaging projections attached to the base. Theseformed engaging projections project from the front surface of the baseto flattened tops, which tops were formed on the contact releasesurface. The flattened tops at least partially overhang the base forminga rim, and are bordered, at least partly, by an edge having an anglewhich is influenced by the acute contact angle.

As mentioned above, there are two generic subsets of methods that allowthe formation of predetermined shapes of engaging projections. In thefirst subset method the polymer particles are deposited onto the contactrelease surface in a predetermined pattern that defines the shape to beformed. The particles are delivered to the contact release surface inselected patterns or shapes by a variety of methods. In a first methodthe particles are projected against a mask having cutout portions thatdefine the shape to be formed. The mask can be fixed in position, withthe result that particles that go through the cutout portion of the maskare deposited as preform projections onto the (moving) contact releasesurface in stripes. An exemplary engaging projection area configurationresulting from this approach (upon transfer of the preform projectionsto a base film) is shown in FIG. 8 a. The deposition of particles can bestopped and started so as to provide interrupted downweb stripes.Alternatively, the mask can move with and at about the same speed as thecontact release surface. In this case, the particles that go through thecutout portion of the mask are deposited on the contact release surfacein the shape defined by the cutout. Some exemplary engaging projectionarea configurations resulting from this approach are shown in FIGS. 8 b,8 c and 8 d. The mask can comprise a disposable film, for example aplastic film with appropriately shaped cutouts. In a preferableembodiment, the mask comprises an endless belt (as discussed later withregard to the embodiment of FIG. 2 a).

The particles are projected onto or through the mask by any of a varietyof means. First, gravity could be used where particles are simplyallowed to fall onto the mask. This method however suffers from theproblem of how to remove the particles that land on the non-cut outportions of the mask. These particles could be removed by vacuum,contact removal, air jets or the like, but there remains the possibilitythat some of these particles later fall through the apertures of themask in areas not intended to have particles, or at the wrong time inregions intended to have particles.

Another way to bring particles onto or through a mask is electrostaticdeposition. In this method the polymer particles are directed toward themask by an electrostatic driving force. This is performed by providingtwo electrodes so as to establish an electric field therebetween. Afirst electrode is positioned so that the mask is between the firstelectrode and the contact release surface. A second electrode ispositioned behind the contact release surface. A voltage is applied tothe electrodes so as to establish an electric field therebetween. Uponthe introduction of suitable particles into the gap between the firstelectrode and the mask, the particles are changed then driven under theinfluence of the electric field in the direction of the secondelectrode. Thus, the particles encounter the mask, with the result thatsome hit the solid portion of the mask and some pass through the cutoutregions and impinge on the contact release surface so as to collectivelyform the desired shape.

Electrostatic deposition is most advantageously performed in a verticalconfiguration with the second electrode positioned above the firstelectrode. In this arrangement the particles are driven upwards, againstgravity, thus the particles that hit the mask fall back down and may becollected and/or recycled, or are otherwise less likely to accidentallyfall onto the contact release surface, which is present behind the maskand the contact release surface. This method also has the advantage ofproviding for more uniform distribution of particles onto the contactrelease surface. All the particles will be like charged and repel oneanother. This will tend to keep the particles evenly distributed andkeep individual particles from forming large number of unified preformprojections. This method is advantageous for providing either uniformdistributions of particles in the discrete regions or over the contactrelease surface as a whole with a uniform distribution of particles tobe formed into preform projections.

As previously described herein, the mask may be stationary or moving intandem with the contact release surface. (An embodiment of the latter isdiscussed in detail later with regard to the embodiment of FIG. 2 a). Inelectrostatic coating, ideally the mask material is such that theparticles that hit the mask do not stick to it via electrostaticattraction.

The polymer particles must also be chosen for their suitability forelectrostatic coating. The primary requirement is that under theinfluence of the imposed electric field, the particle develop sufficientinduced charge such that sufficient force is placed on the particle bythe electric field that the particle moves between the two electrodes.Preferably, the electric force should overcome gravity such that theabove-described vertical configuration can be used. Fortunately, most ofthe materials that are appropriate for forming preform projections(namely, thermoplastic powders such as polypropylene and the like) aredielectric materials (that is, capable of having a charge induced uponbeing placed in an electric field). Suitable particles for forming thepreform projections are also generally small and of low density (thuslight in weight) making them easier to be driven via electrostatic forceupward against the force of gravity.

An alternative embodiment of electrostatic discrete deposition uses asecond electrode that is in the form of a patterned conductive belt.Such a patterned belt, placed behind the contact release surface (abovethe release surface, if in the vertical configuration), moving in tandemwith the release surface, would result in particles being moved towardthe contact release surface primarily in the regions of the releasesurface that have a solid area of the patterned electrode behind them.This eliminates the need for a physical mask interposed between theparticle source and the contact release surface. Such a patterned beltmost conveniently takes the form of a continuous metal belt with holesprovided therein, which can be connected to a voltage source andmaintained at a desired voltage even while moving in an endless loop.(Such an embodiment is discussed in more detail with regard to theembodiment of FIG. 5 a) This arrangement is most suited for depositionof preform projections in a contiguous pattern with discrete empty areastherebetween. If it is desired to provide the preform projections indiscrete regions surrounded by contiguous empty areas, it is possible touse a nonconductive belt with conductive regions provided thereon (forexample, a nonconductive polymeric film with areas of conductive inkscreen printed thereon). It would of course be necessary to provideelectrical connection between the conductive areas, which could be donewith very thin lines of conductive material.

As described previously, the particles are introduced into the spacebetween the first electrode and the mask (if present). Alternatively, inthe absence of a mask, the particles are introduced into the spacebetween the first electrode and the contact release surface. Theparticles should be placed in the gap in whatever manner will allow themto come under the influence of the electric field and be driven towardthe contact release surface. Ideally, this is performed in a uniformmanner. The particles may be sprayed, dropped, blown, or otherwiseinjected into the gap by methods well known in the art. In theabove-described vertical configuration, the particles may be injectedlaterally into the gap by spraying. Alternatively, the particles can bebrought into the gap by means of a carrier belt which, bearing theparticles on its top surface, comes into the gap such that the particlesare free to move toward the contact release surface by the appliedelectric field.

Other methods besides the afore-mentioned electrostatic deposition andgravity-assisted deposition are possible. Alternative methods toselectively bringing particles to a contact release surface inpredetermined shapes or patterns include impacting the particles onto amask by a forced airstream, mechanical projection or conveying, and thelike.

These first generic subset methods are amenable to multistep depositionof particles as preform projections. That is, it may be advantageous toprovide different discrete regions that comprise engaging projectionsthat differ in some feature (for example, color, size, aspect ratio,modulus, etc.). One such way to provide such a product is to process abase film to attach one set of engaging projections, then send the filmthrough an additional processing step to attach a second set. However,this may involve cumbersome handling of the base film. A preferredmethod is to provide a processing line with multiple depositionstations. That is, it is possible to deposit a given set of preformprojections onto the contact release surface, and thereafter depositanother set of preform projections. The second set may be deposited in(separate) discrete regions, or may be deposited throughout the contactrelease surface (which will of course result in some degree of“stacked”) projections. Such a configuration may be provided by means ofa processing line that has two deposition stations positionedsequentially such that the moving contact release surface passes throughone station, then through the other station. After passing through thedeposition stations, the preform projections are transferred to the(same) base film. (An example of this is discussed in additional detailwith reference to the embodiment of FIG. 3 a). In an alternateconfiguration, the first set of preform projections may be deposited onthe contact release surface then transferred to the base film, which isthen fed into the second deposition station for deposition andsubsequent attachment of the second set of preform projections.

In a second generic subset of methods the polymer particles aredeposited onto the contact release surface, which could be uniformly.The predetermined pattern or shape of engaging projections is providedby selectively transferring and attaching polymer particles on thecontact release surface onto predetermined regions of the base. Thisselective attachment can be done by making predetermined regions of thebase more or less receptive to bonding the preform projection polymers.Two basic approaches exist. The first is to provide a base film that haslittle or no ability to bond to the polymer particles used to form thepreform projections, and then imparting regions of higher bondingability onto the surface of the base film. In the use of an adhesivesuch as a PSA to bond the preform projections to the base, it would bestraightforward to provide the PSA on the base only in selected regions(by pattern coating, stripe coating, and the like). In the case offusing (i.e. melt bonding), dissimilar polymeric materials may not bondwell to each other. Thus, for example, the placement of preformprojections of polystyrene onto a base film of polypropylene, (or viceversa) may result in little or no bond formation. However, if acompatibilizing layer is placed upon a selected area of thepolypropylene base film, an enhanced bond may be achieved. Suchcompatibilizing layers can be applied to the base in a patterned ordiscrete or discontinuous manner by a wide variety of methods of theart, including pattern coating, screen printing, vapor coating, plasmacoating, photolithography, chemical vapor deposition, and the like.

Compatibilizing layers may comprise any of the widely known tie layersand bonding layers that are available in the art. All that is necessaryis that the compatibilizing tie layer have sufficient adhesion to thebase and sufficient adhesion to the polymer particle used to form thepreform projection. In this approach, the polymer particles and basefilm may no longer need to be formed of the exact same material, ormaterials that are extremely close or similar in composition. Thisallows the base and the polymer particles to be chosen based on thephysical properties most desired for each. For example, it may bedesirable to chose a base film that is extremely soft and flexible, anda polymer particle that is extremely hard and rigid (or vice versa). Theuse of compatibilizing layers on the base film allows this to be done.An example of this approach is discussed later with regard to theembodiment of FIG. 6 a.

The other approach is to use a base and polymer particles that bond wellto each other, and to apply a masking layer to selected regions of thebase. In one embodiment the masking layer is a permanent layer that isretained on the base and that does not bond to the polymer particles.Such masking layers could be polymeric (for example, coatings such assilicone, fluorosilicone, or Paralene) or metal or metal oxides, forexample. All that is necessary is that the layer does not bond well tothe particles nor is it sufficiently displaceable to permit bonding tooccur through it. Such layers can be applied to the base in a patternedor discrete or discontinuous manner by a wide variety of methods of theart, including pattern coating, screen printing, vapor coating, plasmacoating, photolithography, chemical vapor deposition, and the like. Itis also possible to deposit the masking layer everywhere on the surfaceand to remove it in selected regions, via etching, ablating, and thelike.

In another embodiment the masking layer is provided temporarily, so asto constitute a physical barrier in certain locations to prevent polymerparticles from contacting the base during transfer from the releasesurface. In this case the masking layer may be a film which is usedtemporarily but does not become part of the final product, as describedlater with reference to the embodiment of FIG. 7 a.

The skilled person, familiar with the field of surface energy, surfacetension and wetting, can select a combination of a suitable polymer forthe particles and a contact release surface of a suitable surfaceenergy, and also select particles having a suitable viscosity at thetemperature of the contact release surface that will wet the contactrelease surface within a suitable time. The surface energy of thecontact release surface may be formed by known materials and methods,such as siliconized surfaces, fluorochemicals, corona discharge, flameor the like. The contact release surface must be able to release theparticular polymer particles used, semi-liquefied and solidified. It isknown that certain release surfaces can release certain polymers but areunable to release other polymers. For example, a polyethylene releasesurface can release suitable polypropylene particles but cannot releasecertain polyethylene particles as they tend to weld or fuse to eachother. The word “release” as used herein refers to the phenomenon wherethe particles are detached from the contact release surface without(unacceptable) damage or loss of material of the particles or preformprojections.

Dispersing of the particles onto the contact release surface by gravitycan be performed in any suitable way, for example, by scattering theparticles with a scatter unit. Other methods have been mentioned herein.The particles should be dispersed at a rate per unit surface area sothat they form preform projections where one particle can form onepreform projection, which may merge as discussed above. The particlescan be brought into the at least semi-liquid state before, during and/orafter dispersing of the particles onto the contact release surface. “Atleast semi-liquid” means liquid or semi-liquid. A suitable way ofliquefying will depend on the properties of the selected polymer, andcan include, for example, heating, thinning, solving, emulsifying,dispersing etc.

A solidity (degree or extent of solidification) suitable for contactingand fixing the preform projections on the contact release surface withthe front surface of the base can be decided by the skilled person,depending on the particular circumstances. It will usually, but notnecessarily, mean a more solid state than the one in which the preformprojections have been formed on the contact release surface. Preferablythe preform projections should be solid enough to keep, at least partly,their shape while being contacted with the front surface of the base. Itusually primarily means keeping at least a minimum free height and alsoa suitable edge angle of the preform projections. Setting the necessarysolidity in the preform projections will be material-dependent, and caninclude cooling, drying, heating, crosslinking, curing, chemicaltreatment etc. The preform projections of suitable solidity, sitting onthe contact release surface, can be covered by the base front surfacesuch that the front surface of the base can contact and fix with thepreform projection terminal ends. The terminal ends are the endsfarthest from the contact release surface. Before contacting with thefront surface of the base, the preform projections can be provided, orsupplemented, with further added dispersed particles or the like, whichwill attach to the preform projections. It is possible that the frontsurface of the base is contacted with the preform projections when thepreform projections are in a semiliquid state. In this case it ispossible that after the contacting, and before a final solidification,the preform projections are somewhat lengthened by stretching while thepreform projections are removed from the release surface thereby causingthe preform projections to get slimmer in their middles. A skilledperson can also choose a base flexible enough to permit contactingpreform projections of possibly non-uniform heights. The front surfaceof the base can be smooth but it can also be suitably rough, for exampleroughened with particles or projections previously scattered and fixedon the base. The fixing of the terminal ends of the preform projectionsto the front surface of the base can be obtained for example by,adhering with an added adhesive (for example, a pressure sensitiveadhesive, hot melt adhesive, or UV-cure adhesive), crosslinking withultraviolet irradiation, or it can utilize the inherent adhesion of thecontacting materials (the base front surface or the preform projections)or fusing. Fixing with fusing will be discussed in detail later herein.While fixing, care should be taken in order that the free overhangs orrims, and the actual heights of the preform projections are sufficientlypreserved. For example, an exaggerated sinking or compression of theprojections into the front surface of the base should be avoided. Theproper solidity of the preform projections and the base, suitable for aseparating and removing both from the release surface can be decided bythe skilled person, depending on the particular circumstances. Thesolidity of the preform projections when they are removed from therelease surface will usually, but not necessarily, be a more solid statethan when they are initially contacted with the front surface of thebase. Preferably the preform projections should be solid enough to keep,at least partly, their shape during the separation from the releasesurface. It usually primarily means keeping a suitable overall shape,with particular respect to the edge angle formed, but preserving asuitably strong bond with the front surface of the base is also animportant factor. The base generally should be solid enough to keep itsform and separate the preform projections from the release surface. Thetop surface as formed can be smooth but can also be somewhat roughened,e.g., sandpaper-like or grooved, as known from the art. The top surfacestructure will be largely determined by the contact release surface,which may be essentially flat, even if naturally not planar in the truegeometrical sense. Post treatments could however be used that would makethe top surface not essentially flat, such as a noncontact heattreatment. If small numerous projections are advantageous it ispreferable if, in the methods, that at least some of the separatepreform projections comprise exactly one polymer particle per preformprojection.

It is preferable if, in the methods, at least some of the preformprojections are provided with contact angles 38 of between 10° and 85°,preferably 30° and 80°. This would be the range of contact angles formost of the individual preform projections. For a preferred embodimentthis range would be the mean contact angle for the preform projections.

It is preferable if, in the methods, at least some engaging projectionsare provided with a profile in which, in each side view thereof, theengaging projection strictly tapers (preferably is strictly convex) fromthe flattened top or top edge to the front surface of the base. This isusually very easy to achieve by this method which typically createssemi-lenticular preform projections, like water drops sitting on asuitable surface. In the methods, non-thermoplastic and thermoplasticpolymer particles can be used, the selection being based on necessarystrength, required surface energy, cost etc. However it is preferableif, in the methods the polymer particles are thermoplastic polymers.

If drops of liquids are deposited onto a solid contact release surfaceand if the surface energy of the release surface is somewhat higher thanthe surface energy (or surface tension) of the liquid, the liquid willtypically perfectly wet the solid, with a contact angle of zero. Withliquids, each “solid-liquid” pair has a contact angle, between zero and180°, with which the liquid drop will, approximately, wet the solid.With semi-liquid, e.g., softened thermoplastic, particles, the processof forming a contact angle is a time-temperature phenomenon. With solidcontact release surfaces of high surface energy a liquid polymer willwet perfectly if given enough time. If this high surface energy solidcontact release surface is kept hot, and a cold solid particle is placedthereon, a process is started in which the contact angle transforms overtime, from an initial obtuse angle towards the final zero contact angle.By interrupting this transformation process, e.g., by a suitablecooling, one can achieve any desired contact angle. Therefore highsurface energy solid contact release surfaces are useful in the processof the invention. However, the higher the contact release surface'ssurface energy, the more difficult it is to finally separate the releasesurface from the preform projections. Also if the surface energy of thecontact release surface is too high in relation to that of the polymerparticles there is greater opportunity for unintentional operator errorforming a preform projection that is excessively wets the contactrelease surface. The danger of overwetting the contact release surfaceis lower if the surface energy of the contact release surface is nothigher than the surface energy of the particle plus 60 mJ/m².

High surface energy contact release surfaces also might cause theengaging projection's edge angles being too sharp creating rims that aretoo thin and which might possibly break off during later use, creatingundesired contamination. It is likely sometimes better to accept largercontact or edge angles to provide enhanced security against engagingprojections forming with thin weak edges and rims. Therefore it can bepreferable if the methods comprise providing a contact release surfacewhose surface energy is lower than the first surface energy (that of theparticle). In this case the edge angle in the product can be determinedby material selection rather than by on-line operating parameters. Alsothe lower the surface energy of the contact release surface, the easierit is to finally detach the preform projections therefrom. However acertain degree of force needed for detaching preform projections fromthe contact release surface can be beneficial. Some preform projectionscan be weakly fixed to the front surface of the base. Namely the fixingstrength is lower than desired for its intended end use resulting insome engaging projections possibly breaking loose during use. This is adifficult to detect defect. Therefore it is preferable if the contactrelease surface's surface energy is higher than the first surface energy(that of the particle) minus 23 mJ/m². With a contact release surface ofthis level the separation force for detaching preform projections fromthe contact release surface may be high enough to remove projectionsweakly fixed to the base front surface thereby providing an on-linefault-detection and correction mechanism.

It is preferable if, in the methods described hereinabove forthermoplastic preform projections (which can also be termed protrusionsthroughout), the fixing of the front surface of the base with theterminal ends of at least some of the preform projections comprisesfixing by heat or fusing.

Fixing by heat can include melting one or the other of the preformprojections or the base front surface, depending on the materials andpressure etc. Preferably both the preform projections and the frontsurface of the base are allowed to potentially melt, and are therebyfused. Fusing is a fixing of the preform projections to the frontsurface of the base by heat. In this case the preform projections aremade up of particles well suited for both sharpening by the releasesurface, from below, and the covering and fixing to the base by fusing,above. The particles must be liquefied enough during the fusing tosuitably form the contact angle, but must remain solid enough, to permitkeeping their edge angles. It is preferred that the thermoplasticpolymer particles have a melt flow rate of between 1 and 90 grams per 10minutes at the conditions appropriate for the selected polymer.

In the subsequent step of the above method, the fixing by heat comprisesmaintaining the contact release surface at a temperature lower than thesoftening temperature of the polymer particles or preform projectionswhile contacting the front surface of the base with the attachment endsof at least some of the preform projections. The back surface of thebase is preferably heated by subjecting it to a heated gas. However,other heating methods such as radiant or IR heat may be used. If heatedgas is used, the gas pressure at the back surface of the heated base istypically higher than the pressure (e.g. a gas pressure) at the frontsurface of the heated base, thereby pressing the heated base against theattachment ends of at least some of the preform projections to enhancethe fixing thereof to the base. The pressure difference may be enhanced,for example, by applying vacuum from beneath the contact release surfaceor the front surface of the base.

Also, in these methods it is not a great problem if the preformprojections are of different heights, as long as a sufficiently pliablebase, capable of bending down to reach the lower preform projections, isprovided. It is especially useful if the whole base is thermoplastic andis actually softened, thereby made soft and flexible, easily bending oreven stretching when hot (This may be advantageous particularly ifregions of preform projections differing in height are present, asdiscussed previously). If desired the base can be fully softened, wherefully softening means softening of all components, layers thereof, e.g.in case of a composite, above a softening temperature.

After the separation of the base from the release surface, some preformprojections, not fixed to the base, may remain on the contact releasesurface. These are usually very tiny residual polymer particles, whichmay melt into, and go away with, particles dispersed later on thecontact release surface. Still by regularly providing for their removalfrom the contact release surface, the process can be made more uniformand secure. Therefore it is preferable if the method further comprises:

before the dispersing of the multiplicity of polymer particles on thecontact release surface;

heating the contact release surface to a temperature higher than thesoftening temperature of both the polymer particles and the frontsurface of the base;

contacting the front surface of the base with the heated contact releasesurface thereby softening the front surface;

suitably pressing the softened front surface against the heated contactrelease surface thereby fusing the polymer particle contaminationresidue into the front surface of the base;

providing, for the contact release surface and the base, temperaturessuitable for separating the base from the contact release surface;

separating the base from the release surface, thereby cleaning thecontact release surface.

This method uses the thermoplastic character of both the particles andthe front surface of the base for cleaning the contact release surface.During the steps above, the small amount of residual polymercontamination goes away with, and usually disappears in the frontsurface of the base. The base can then be utilized as usual. In acontinuous operation, e.g. comprising rolls or conveyors, the releasesurface can be cleaned with every revolution, before each dispersing ofparticles, thus always keeping the cumulative contact release surfacecontamination at low levels.

While the preform projections are being fused to the front surface ofthe base, the base is typically above the release surface where it issupported by the preform projections and bridges the space between them.If the front surface of the base is above its softening temperature, anymolecular orientation therein may cause problems by shrinking at leastthe bridging portions of the sheet-form base. That can be avoided, forexample, with using a composite base with a suitable backing resistantto shrinking. For example a base, comprising a polyester film, or paper,backing and a polyethylene layer coated thereon as front surface, canpotentially withstand the shrinking that may occur in the base. Howeverif shrinkage is a problem it is preferable if the base is free ofmolecular orientation when fusing the preform projections or particles.Molecularly oriented films can be pretreated by contacting the frontsurface of the base with a heated release surface (which could be thecontact release surface), thereby rendering the front surface of thebase essentially molecularly un-oriented.

Heated gas (preferably air) at an elevated pressure can best be providedwith gas nozzles ejecting heated gas. If the base is moved in front ofthe output orifice of the nozzles so that its back surface is contactedwith the ejected hot gas then the base softens. At the same time, thehot gas ejected from the nozzles creates and maintains a gas flow alongthe back surface of the base, typically parallel to the travelingdirection of the base. If the nozzles are fixed and the base is movingin a machine direction, the hot gas flow will have a directionessentially both parallel and opposite to the machine direction. The hotgas flow, e.g. hot air flow, will exert a pulling force on the softenedbase, dragging the back surface of the base. That will tend to stretchthe softened base. The faster the gas flows, the stronger thisstretching effect will be. With a low throughput arrangement, i.e., withlow hot gas velocities, and especially with a thick base, a base whichis essentially free of molecular orientation can be used. In case ofhigher throughputs and higher gas flow rates, and especially with athinner base this machine direction stretching of the base can be verysignificant, which can be undesirable. For example, stretching of thebase in a lengthwise, machine direction can make it difficult to controlthe thickness of the fastener or can result in rolls of unspecifiedlength. Stretching can also lead to accidental breaking by thinning,tearing apart the base.

The effects of stretching can be counterbalanced by providing a suitablemolecular orientation in the base. The problem of stretching can besolved if the base is provided with a heat-shrink potential in themachine direction. The heat of the gas will relax the orientation in thebase, i.e., will tend to shrink the base, which will counteractstretching by the heated gas flow. Therefore, in a variation of theinvention method, one or more gas nozzles, adapted for ejecting heatedgas, are provided. The back surface of the base is contacted with theheated gas ejected by the one or more gas nozzles while the base movesrelative to the one or more gas nozzles. The direction in which the baseis moving is the machine direction and is essentially within the planeof the base. The base preferably has a heat-shrinkability in the machinedirection (the lengthwise heat shrinkability) of at least 1 percent. Thefixing by heat includes heating the base above a heat shrink temperaturethereof.

As used herein, “heat-shrinkability” in a direction shall mean, in thecontext of a material such as the base material, that the material iscapable of being decreased in its length in the given direction, ordimension, in response to the transmission of thermal energy into thematerial. The “heat shrinkability” of the material is a percent valueand equals 100 percent times the difference between its pre-shrinklength and post-shrink length, divided by its preshrink length, in thegiven direction. The post-shrink length, in a given direction, of thematerial means the length of the material, in the given direction, aftershrinking the material, such as at a temperature of 170° C. for 45seconds. Shrinking can be determined, for example, by immersing thematerial into hot silicon oil and letting it freely shrink. It was foundthat using temperature of 140° C. for 14 seconds relaxes essentially allthe shrink in usual polymer materials. As used herein, the “shrinkingtemperature” of a material refers to the temperature at which thematerial, exposed to an increasing temperature, starts to heat-shrink.

The advantage of this variation of the methods of the invention is thatit helps counteract stretching effects exerted on a softened base byejected hot gas flow. With high production rates lengthwiseheat-shrinkability higher than 1 percent can provide improved results.Therefore it is preferable if, in this variation of the methods, a basehaving a lengthwise heat-shrinkability of at least 10 percent, morepreferably at least 20 percent, more preferably at least 30 percent,even more preferably at least 40 percent, and even more preferably atleast 50 percent is provided for the contacting and the fixing dependingon the forces created by the hot gas flow and the production rate.

The stretching effect, exerted on the base by a lateral hot gas flow isless significant, or even close to zero (depending on the details of thenozzle arrangement) in the crosswise direction, i.e., in the directionperpendicular to the direction of the traveling path of the base (in amachine it is called the cross machine direction). Therefore, if a basehas a high heat-shrink potential, or high heat-shrinkability in thecrosswise direction, the edges of the base can shrink or neck in, whichresults in folding or wrinkling when contacted with the hot gas. This isundesirable. Therefore it is preferable if the heat-shrinkability, ofthe base in its in-plane direction perpendicular to the main or machinedirection is either zero, or lower than the lengthwiseheat-shrinkability. “Zero crosswise heat-shrinkability”, as used herein,includes the case in which the base exhibits an increase in length, orstretch, rather than shrinking, in the crosswise direction when exposedto heat. The advantage of this difference in heat shrinkability is thatit provides a differentiated counteraction to the differentiateddragging effects of the hot gas flow on the softened base in the twoorthogonal dimensions. Generally the heat-shrinkability, of the base inits in-plane direction perpendicular to the main direction (thecrosswise direction) is lower than 50 percent. Preferably, the crosswiseheat-shrinkability is lower than 40 percent, more preferably lower than30 percent, even more preferably lower than 25 percent, depending on theforces created by the hot gas flow and the production rate. On the otherhand, the base heated by the hot gas will exhibit a crosswise thermalexpansion which may cause wrinkles in the product. That can becounterbalanced with a suitably low, but positive level ofheat-shrinkability provided in the base in the crosswise direction.Therefore it is preferable, if, in the aforementioned situation, thecrosswise heat-shrinkability of the base is at least 1 percent.

The methods of the invention also include the step of dispersing thepolymer particles on the contact release surface so as to form separatepreform projections. Preferably it should be avoided that many or mostparticles, which will form the preform projections, touch adjacentparticles, or preform projections, before the preform projections arecompleted and solidified (However, such an instance may be preferable ifit is desired to form “stacked” projections as described earlier).Premature particle contact results in a unifying of the neighboringparticles or preform projections. However if in a fastener the engagingprojections are close to each other, the fixing strength of the fasteneris generally higher, i.e., the fastener performs better. As in thismethod the dispersing, e.g., scattering, of the particles is typicallyimplemented as a stochastic process, the closeness of the projectionsusually does not reach the theoretically possible maximum value, i.e.,the projections could even be a bit closer to each other in the endproduct. After the fastener is completed, a subsequent moderate heatshrinking of the base can improve the relative closeness of the fastenerengaging projections if desired. However, in order to perform this stepthe base of the formed fastener must have some heat-shrinkability.Therefore it is advantageous if, in this variation of the methods of theinvention, the formed fastener base, has a residual lengthwiseheat-shrinkability of at least 1 percent. Preferably, a formed fastenerbase, has a lengthwise heat-shrinkability of at least 5 percent, morepreferably at least 10 percent, more preferably at least 15 percent,even more preferably at least 20 percent, even more preferably at least25 percent in this embodiment. In this method the formed fastener issubsequently heat-shrunk at least in the main direction. Thisheat-shrinking can be by any suitable way of transmission of thermalenergy into the formed fastener but preferably in a way such that theacute contact angles, and the geometric features of the engagingprojections in general, are kept essentially intact or are at leastsuitably protected. Preferably the heat energy is transmitted into theformed fastener from the back surface of the base of the fastener. Forexample this could be done by depositing hot material, e.g., hot meltadhesive, onto the back surface of the base as part of a fixing of thefastener to a substrate. The heat-shrinking should be kept at a lowenough level so as to keep adjacent engaging projections separate fromeach other sufficient for the engaging fibers of a female fastener partto penetrate between adjacent engaging projections. Preferably thefastener base is heat-shrunk by about 0.1 to 25 percent or less.

Economical base materials, e.g., blown or cast thermoplastic polymerfilms, may not be readily or economically available with the appropriateheat shrink parameters, as these films often have higherheat-shrinkability values than are required. A suitable base can beproduced from these economical base materials with a pre-treating step.The pre-treating suitably decreases the heat-shrinkability of thematerially in a controlled, partial relaxing of its molecularorientation without letting it shrink entirely. Namely, if a high heatshrinkable film is mechanically kept from freely shrinking and issimultaneously kept hot or softened, its heat-shrinking potential orheat-shrinking capability will gradually decrease with time without thematerial actually decreasing in length or area to the correspondingextent. Therefore it is preferable if these types of base materials arepre-treated prior to contacting and fixing of the base material frontsurface with preform projections. The pre-treating of the base comprisesproviding a pre-treating release surface;

heating the pre-treating release surface to a suitable temperaturehigher than the softening temperature of the front surface of the base;

contacting and pressing the front surface of the base with thepre-treating release surface thereby softening the front surface;

keeping the softened front surface in contact with the heatedpre-treating release surface while preventing the base from shrinkingfreely, for a suitable period of time thereby decreasing at least itslengthwise heat-shrinkability;

providing, in the pre-treating release surface and in the base,temperatures suitable for separating the base from the pre-treatingrelease surface; and

separating the base from the pre-treating release surface.

The release surface used for the pre-treating, i.e., the pre-treatingrelease surface can be similar to or different from the contact releasesurface discussed above. The pre-treating release surface must be ableto suitably release the base at the right time. The base preferably isessentially prevented from any shrinking, e.g. in order to maintain itsregular dimensions, but mainly its length. This could be done by keepingthe base front surface in full contact with the pre-treating releasesurface. For that purpose, the tack between the softened front surfaceof the base and the pre-treating release surface (e.g., apolytetrafluoroethylene surface) can be exploited. In order to do thisresidual air between the two surfaces should preferably be removed whilecontacting and pressing the base to the pre-treating release surface.The lengthwise heat-shrinkability of the base is decreased to a suitablevalue while the crosswise heat-shrinkability rate may (and preferablywill) also be decreased. The longer the contact time and higher thetemperature, the more the decrease in the heat-shrinkability will be,and vice-versa.

It may be desirable if the length of the base at the start of theprocess is not too much different from, or equivalent to, the length ofthe fastener product made therefrom, at the end of the process. As itwas seen, this can be influenced by setting the right lengthwiseheat-shrinkability in the pre-treated base. Therefore it is possiblethat in the pretreating process a decreased value of lengthwiseheat-shrinkability is achieved such that the pre-treated base length isessentially the same as the formed fastener length. Within this methodstep if the balance decreased value can be continuously maintained byregulating, during the pre-treating of the base, one or both of;

the temperature of the pre-treating release surface, and

the duration of the base contact with the pre-treating release surface.

A practicable manufacturing arrangement using a pre-treating step isusing an endless release belt with a release outer belt surface kept ina circulating motion along a belt path; and

for pre-treating the base a first portion of the outer belt surface,being at a first location of the belt path, is used as the pre-treatingrelease surface; and

for forming the fastener from the pre-treated base a second portion ofthe outer belt surface, being at a second location of the belt pathsuitably displaced from the first location, is used as the contactrelease surface; and

the base is provided in the form of a continuous base film kept in amotion synchronous with the belt, and is contacted with the outer beltsurface at the first and second locations.

This solution is advantageous because a single release belt is used forpre-treating the base and further producing the fastener from thepre-treated base, which can provide for a zero length-difference betweenthe initial base and the final product. This zero length-difference isdesired to conveniently use the same belt, running in all of its pointswith the same speed, for two different purposes, i.e., for pre-treatingthe base on the one hand and for depositing the particles to formpreform projections and contacting and fixing the pre-treated basetherewith on the other hand. The release surface speed at the firstlocation is desirably the same speed as the initial base speed and therelease surface speed at the second location is desirably the same speedof the final formed fastener product. If the decreased value oflengthwise heat-shrinkability of the base provided by the pre-treatingdeviates from a balance value, this section of the base when in freecontact with the belt between the first and second belt locations willtend to either get shorter or longer. That can be detected by providinga base film buffer with dancing roller(s) and detecting the trend ofmotion of the dancing roller(s). If the free section of the base filmbetween the two belt locations should shorten then the lengthwiseheat-shrinkability of the pre-treated base could be decreased and viceversa. The lengthwise heat-shrinkability of the pre-treated base can bedecreased more by elevating the temperature of the belt at the firstlocation and/or lengthening the first portion of the outer belt surfacealong which the belt and the base are in contact thereby lengthening theduration of the pre-treating of the base, and vice-versa. This solutionhas an additional advantage that the outer release belt surface iscleaned from any potential polymer particle contamination by contactingthe softened thermoplastic front surface of the pre-treated base withthe release belt with every revolution of the belt.

It is further the object of the present invention to provide a newfastener product, readily achievable through the methods above, havingcorresponding advantages.

The product of the invention is a hook fastener for engaging with a loopfabric, comprising a sheet-form base having a front surface with amultiplicity of solid and preferably essentially solid or rigid engagingprojections. The engaging projections have a top end and an attached end(which can also be termed throughout as a foot). The attached end isjoined to the base front surface at a fixing portion. In that there is afixing of the engaging projections to the front surface of the base, thebase and the engaging projection can be formed of different materials orthe same materials. The engaging projections projecting from the basefront surface can be formed to have an essentially flat top by thecontact release surface. However, generally the top end has been subjectto a deformation treatment such that it has a different form than theattached end of the engaging projection. If the deformation surfaceand/or the contact release surface are flat then the top end will becorrespondingly flat as formed. The top will also generally overhang thebase at least partly, where the overhanging portion is also referred toas a rim.

The top of the engaging projection as formed will also have a definiteedge bordering the top. The engaging projection will also have a mantlesurface, meeting the top along the edge, extending from the edge of thetop to the attached end of the engaging projection at the front surfaceof the base. The mantle surface and the top surface close to form acuteedge angles generally along the entire edge.

During use, the engaging projections should essentially behave as solidbodies fixed to a base, which preferably is flexible. As used herein, astrictly convex contour line of an engaging projection, in a side viewis convex when looking from the outside and not straight. A strictlyconvex shape for the lower surface of the overhanging rim or mantlesurface has been found to be beneficial because it gives a relativelylarge thickness to the at least one engaging projection. In at least oneside view of the at least one engaging projection, the mantle surface ispreferably strictly convex at least at a part thereof adjacent to theedge. This convex shape provides strength to the edge of the rimoverhanging the base. A convex shape also effectively leads engagingfibers down towards the base, thereby reducing torque load on theengaging projections and the base where they are attached, as wasdiscussed above. In a different preferred embodiment the engagingprojection is strictly tapered from the top to the front surface of thebase in at least one side view of the at least one engaging projection.

The invention fastener has desired advantages. It can provide good shearstrength engagement with low loft loop fabrics, including ultra thinnonwoven fabrics. It can also provide shear strength in all directionsand is therefore essentially isotropic. The invention fastener can alsobe manufactured with dense and small projections with generally flattops and a flexible base making it skin-friendly. There is greatflexibility in selecting the base relative to the particles forming theengaging projections. The invention fastener can also be low cost.

Preferred forms of the product, some of them corresponding to thepreferable embodiments of the methods described above, can offer variousadvantages.

First it is advantageous if the fastener engaging projections, in atleast one side view of the mantle surface are strictly convex at leastin all portions adjacent to the side edge. Further, it is advantageous,if the fastener engaging projections in each side view of the mantlesurface are is strictly convex at least in all portions adjacent to theside edge. It is also advantageous if the fastener engaging projections,in each side view strictly tapers from the top to the front surface ofthe base. The mantle surface 17 and the top surface 14 of the engagingprojections define edge angles 18. These edge angles 18 areadvantageously along the entirety of the edge and have an angle ofbetween 15° to 85° or between 30° and 80°. It is further advantageous ifthe fastener engaging projections 13, are strictly convex in at leastone side view of the entire mantle surface 17. This effectively leadsthe engaging fibers down to the front surface 20 of the base 4, toreduce torque load. It is further advantageous if the fastener comprisesengaging projections 13, which are strictly convex in each side view ofthe entire mantle surface 17.

It is also advantageous if, the material of the front surface of thebase differs from the material of at least one engaging projectionsmantle surface where they are attached. Such an arrangement can beachieved by the use of base film and preform projections comprised ofdifferent materials, with the use of compatibilizing layers ifnecessary, as discussed previously. It is even more advantageous if thematerial of the front surface of the base is softer than the material ofthe mantle surface of the at least one engaging projection asdetermined, for example, by differing Shore hardness values.

It is also advantageous for some uses if the fastener base iselastically extensible within a plane of the base, and the material ofthe mantle surface of the at least one engaging projection is nonelastomeric. The base can comprise elastomer materials including elasticlaminates or the like. This can make an elastic fastener product, whichcan be especially beneficial, for example, with diapers and wrappingtapes.

In addition, the invention fastener can also be used in other fields,such as in self adhesive fastener tapes for fixing carpets or polymersheets to floors or tiles and fabrics to walls of a room.

The invention fastener can also be formed on the surface of a variety ofbase materials. This could be a film as described above but could be anysuitable surface such as a fabric, nonwoven, metal sheet or foil, moldedplastic, paper, breathable film, laminate etc, as described above forthe first method. For example, engaging projections could be formed on awater insulating membrane used for insulating flat roofs of buildingsagainst rain. This membrane could then be fixed on top of a nonwovenfelt on the roof. This system would provide water insulation incombination with a beneficial, lateral vapour migration in the felt,under the insulating membrane.

As it has been said, it is a further object of the present invention toprovide improved disposable diapers using the invention fastener.

In this aspect, a disposable diaper comprises:

a bodyside surface;

an opposite, outer surface, comprising a nonwoven fabric;

at least one male fastening component of the present invention forfixing the diaper about a wearer;

at least one female fastening component, comprising fabric, forseparably engaging with the at least one male fastening component duringthe fixing. The female fastening component may be formed by the nonwovenfabric on the outer surface of the diaper. The separable engagementbetween the at least a portion of the nonwoven fabric of the outersurface of the diaper and the at least one male fastening component ofthe invention preferably has a shear strength of at least 4.9N.

The term “diaper”, as used herein, also includes infant training pants,incontinence garments and the like. The said portion of the nonwovenfabric of the outer surface can be a strengthened portion where, thefibers of the nonwoven of the outer surface take part in engaging withthe male fastening component. The said portion can be strengthened, forexample, by providing a sufficiently stiff film layer under the nonwovenor by impregnating the nonwoven of the outer surface etc. The term“shear strength” refers to a peak shear strength or force achievedduring a shear separation of the male fastener from the female fastenercomponent. An appropriate selection of the nonwoven on the outer surfaceof the diaper and the male fastener component of the present inventionwill result in the fastener being capable of engaging with the nonwovenouter shell of the diaper strongly enough to securely keep the soileddiaper in a folded state without a separately provided loop. With asuitable selection of a nonwoven on the outer surface of the diaper, thefastener can be attachable to any suitable point of the diaper outershell and the attachment of fixing is comfortable and secure.Preferably, the whole of the nonwoven of the outer surface is such asuitable nonwoven.

To make it even more secure, it is preferable if, in the diaper, theseparable engagement, between the engagable portion of the nonwovenfabric of the outer surface and the at least one male fasteningcomponent of the invention, has a shear strength of at least 9.8 N.

In an even more preferable diaper, the at least one female fasteningcomponent is constituted by at least a portion of the nonwoven fabric ofthe outer surface.

Such a selection of the nonwoven of the outer surface of the diaper, andthe suitable kind of fastener makes using of a separate frontal tapecomprising a special loop fabric in the landing zone unnecessary. Thisprovides considerable cost saving. It just needs a suitable surface areaselected for the fastener to achieve a desired fixing strength forsecuring the diaper around a wearer during use.

It is even more preferable, if in the latter diaper, the separableengagement between at least a portion of the nonwoven fabric of theouter surface of the diaper and the at least one invention malefastening component has a shear strength of at least 2.5 N/cm². Here thenecessary shear strength is specified as a shear strength specific of 1cm² unit area of contact surface between the nonwoven and the fastener.

To make it even more secure, it is further preferable if, in the diaper,the separable engagement, between at least a portion of the nonwovenfabric of the outer surface and the at least one male fasteningcomponent, has a shear strength of at least 3.5 N/cm².

It is a further object of the present invention to provide an improvedwrapping tape. Such wrapping tape has a first side with an exposedtextile or nonwoven material, and an opposite second side, comprising amale fastening component of the present invention suitable for engagingwith the textile or nonwoven material for fixing the wrapping tapearound an object. The textile or nonwoven material also includes lowloft fabrics with some free fibers capable of mechanically engaging withthe male fastener materials of the present invention. The advantages ofthis wrapping tape are that it has fine touch, is easy to write uponwith ink, can be flexible, extensible or stretchable, is inexpensive,and is novel in its appearance. With a porous, e.g., micro-perforated ornonwoven, base and a suitable nonwoven loop textile, this wrapping tapeeven be used as house wrap.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is made to the method depicted in FIG. 1 a. Using a subsetmethod of the invention, polymer powder granules are provided, aspolymer particles 36. A base 4 sheet is fed into the system from asuitable source. A contact release surface 40 is provided on a releaseconveyor 39 that is driven around two drive rollers 11. The contactrelease surface 40 is kept horizontal.

At the beginning of the operation cycle, the horizontal contact releasesurface 40 is kept at an elevated temperature by a hot plate 24. Thiscould be done under the release conveyor 39, though further hotchambers, on the top side of a release conveyor, could also be utilized.A scatter unit 42 is used to evenly disperse the polymer particles 36onto a stationary mask 31, (a perspective view of a possible stationarymask 31 is shown in FIG. 1 b), with solid regions 33 intersectingfalling particles and open areas 32 allowing particles to fall onto themoving release surface 40 in a predetermined pattern. The mask couldalso in this version be apertures built into the scatter unit 42. With astationary mask the particles will be deposited in continuous rows inthe continuous method shown in FIG. 1 a. The rows can be madediscontinuous by interrupting the flow of particles for a period oftime. The rows can be made to oscillate if the stationary mask is movedin the crossweb direction in a oscillatory fashion. The particles aredistributed on the contact release surface 40 to form preformprojections 37. The release surface 40 can be cooled prior to theheating element 24. Cooling is also important for later preserving thecontact angle of the preform projections 37, and can be provided by asteel cooling plate 45 at a controlled temperature under the contactrelease surface 40. The cooled preform projections 44 are made solid andsuitable for contacting with the front surface 20 of the base 4. Thebase 4 is laid over the preform projections 44 on the contact releasesurface 40. The front surface 20 of the base 4 contacts the terminalends of the preform projections 44. A hot air blowing unit 23 can befixed above the back surface 3 of the base 4. Hot gas 21 is blown on theback surface 3 of the base 4, which could be done while the releaseconveyor 39 and the base 4 are together kept in motion in a lateraldirection 25. Each point of the base 4 is exposed to the hot air for atime sufficient to soften and fix the terminal ends of the preformprojections 44 to the front surface 20 of the base 4. Then the base 4 iscooled, which could be done by air blower 12. The base 4, with theengaging projections 13 fixed thereto, is separated and removed from thecontact release surface 40, and is then wound up on a reel (not shown).

Using this method the engaging projections 13 formed will have flattenedtops 14, with a rim overhanging the base 4 typically in all directions,and bordered, typically all around, by an edge 15 whose angle 18essentially corresponds to the contact angle 38. The vast majority ofthe engaging projections 13 will strictly taper (strictly convex), ineach side view thereof, from the flattened top 14 to the attached end 16at the front surface 20 of the base 4 (This also applies to the engagingprojections discussed hereafter).

Reference is made to the method depicted in FIG. 2 a. Using a subsetmethod of the invention polymer powder granules are provided, as polymerparticles 36. A base 4 sheet is fed into the system from a suitablesource. A contact release surface 40 is provided on a release conveyor39 that is driven around two drive rollers 11. The contact releasesurface 40 is kept horizontal. A moving mask 41 is provided in the formof an endless belt.

At the beginning of the operation cycle, the horizontal contact releasesurface 40 is kept at an elevated temperature by a hot plate 29. Thiscould be done under the release conveyor 39, though further hotchambers, on the top side of a release conveyor, could also be utilized.A scatter unit 42 is used to evenly disperse the polymer particles 36onto the moving mask 41 (A perspective view of a possible moving mask 41is shown in FIG. 2 b. This mask would serve to deposit particles in apattern of squares and circles). Solid regions 33 of the mask 31intersect falling particles and open areas 46 of the mask 31 allowparticles to fall onto the release surface 40 in a predetermined patterndetermined by the mask when the moving mask 41 and the contact releasesurface 40 are moving at the same relative speeds. With a moving maskthe particles can be deposited in discrete shapes in the continuousmethod shown in FIG. 2 a. In this case the mask should be rotating atapproximately the same speed as the release surface 40, at least suchthat the particles from one mask open area 46 do not end up gettingrandomly scattered on the release surface 40 or merged with particlesfrom an adjacent open area 46. If it is desired to provide the shapedregions (e.g. squares, circles, etc.) with minimum distortion, the maskshould move in tandem with the contact release surface; that is, at veryclose to the same speed. The regions with particles could be distributedin other patterns if the moving mask rows are made to oscillate or movein the in the cross direction. As in the method of FIG. 1, the particlesare that are distributed on the contact release surface 40 form preformprojections 37, then form cooled preform projections 44, then arecontacted with and attached to the front surface 20 of base 4, asdescribed for the embodiment of FIG. 1. Particles that intersect thesolid areas 43 of mask 41 may be removed, for example by contacting themoving mask with a sticky roll, vacuum agitation or the like. Ideallythe particles are removed for recycling to the scatter unit 42, forexample by use of vacuum scavenging system 45.

A further subset method is depicted in FIG. 3 a. A first type of polymerpowder granules are provided, as polymer particles 36. A base 4 sheet isfed into the system from a suitable source. The contact release surface40 is provided on a release conveyor 39 which is driven around two driverollers 11. The contact release surface 40 is kept horizontal. A firstmoving mask 41 and a second moving mask 41′ are provided in the form ofendless belts.

At the beginning of the operation cycle, the horizontal contact releasesurface 40 is kept at an elevated temperature by a hot plate 24. Thiscould be done under the release conveyor 39, though further hotchambers, on the top side of a release conveyor, could also be utilized.In a first deposition station 88, a first scatter unit 42 is used todisperse the polymer particles 36 onto the first moving mask 41 (Aperspective view of a first moving mask 41 is shown in FIG. 3 b.). Solidregions 33 of the mask intersect falling particles and open areas 46allow particles to fall onto the contact release surface 40 in apredetermined pattern. Movement of the mask 41 with the contact releasesurface can be synchronized as described in the method of FIG. 2 a. Theparticles so deposited form the first type of preform projections 37 indiscrete areas on the contact release surface. Optionally, the depositedpreform projections 37 can be cooled as previously described. Thecontact release surface 40 is then passed through a second depositionstation comprising a second moving mask 41′ and a second scatter unit42′ which is used to disperse a second type of polymer powder granules36′ (A perspective view of a possible second moving mask 41′ is shown inFIG. 3 c). Solid regions 33 of the mask intersect falling particles andopen areas 46 allow particles to fall onto the release surface 40 insecond areas of the contact release surface in a predetermined pattern.Movement of the second mask is synchronized with the contact releasesurface as done with the first mask. The contact release surface may beheated (or reheated, if a cooling step was used subsequent to the firstdeposition) via second heating element 24 as done for the firstdeposition. The particles so deposited form the second type of preformprojections 37′. The contact release surface bearing the preformprojections is then passed by cooling element 45 so as to form cooledpreform projections 44 and 44′, after which base 4 is contacted with theterminal ends of the cooled preform projections attaching them to thebase and forming engaging elements 13 and 13′, in the manner describedfor the embodiment of FIG. 1 a. Vacuum scavenging systems (not shown) asdescribed in FIG. 2 a may be used to retrieve the polymer particles thatintersected the solid areas 33 of mask 41. This embodiment would serveto provide a base film bearing rows of discrete circles of engagingprojections of one type, and discrete squares of engaging projections ofanother type.

The method depicted in FIG. 4 a is a further first subset method of theinvention. Using this method of the invention polymer powder granulesare provided, as polymer particles 36′. A base 4 sheet is fed into thesystem from a suitable source. The contact release surface 40 isprovided on a release conveyor 39 that is driven around two driverollers 11. The contact release surface 40 is kept horizontal. Anelectrostatic deposition unit 52 is provided, comprising two electrodes.Electrode 54 is held at low voltage (typically, zero or ground voltage)while electrode 53 is held at a higher voltage. Electrode 53 ispositioned underneath a moving mask 41 while electrode 54 is positionedabove a contact release surface 40. Moving mask 41 is provided withsolid regions 43 and with open areas 46, and can be synchronized withthe speed of contact release surface 40 as described above.

At the beginning of the operation, particles 36 are dispensed into avertically configured electrostatic deposition unit 52 (not shown) suchas by being injected laterally into the gap between lower plate 53 andmoving mask 41. This may be done by means of e.g. spraying the particlesor bringing them into the gap via a belt conveyor from which theparticles are dislodged by the electric field. Or, the electrode 53could be a rotating drum electrode, a belt electrode or the like forboth conveying and charging the particles. Under the influence of theelectric field established by electrodes 53 and 54, particles 36 developa charge to comprise charged particles 36′, and are then drivenvertically upwards. The charged particles 36′ that penetrate through theopen areas of moving mask 41 continue to move upwards until they impingeon contact release surface 40. The charged particles may be held on thecontact release surface 40 against the force of gravity by the residualelectrostatic force between the particles and the contact releasesurface until the contact release surface moves such that the particlesare atop the release conveyor and no such assistance is necessary. Therelease conveyor then continues such that the particles are carried intoproximity with heating element 24 (as in the configuration illustratedin FIG. 4 a). Alternatively, heating element 24 can be placed such thatthe particles 36′ are heated immediately upon deposition (as in theembodiment described with reference to FIG. 1), so that wetting forcesmay assist in holding the particles on the release surface, until therelease conveyor 39 moves sufficiently such that the particles 36′ areon the upward facing surface of the release conveyor 39. Subsequentprocessing to contact and attach the preform projections 36′ to the basefilm are as described previously. Particles that intersect solid areas43 of mask 41 may fall off on their own due to gravity (once the movingmask carries them out of the electric field), or can be removed such aswith a vacuum scavenging system as described for FIG. 2 a.

The method depicted in FIG. 5 a is a further subset method of theinvention This method is similar to that of FIG. 4 a except that no maskis used; rather, electrode 54 is provided as a rotating patterned beltelectrode, e.g. a metal belt electrically connected to counterpartelectrode 53. Moving belt electrode 54 is positioned behind (above) themoving contact release surface 40 and is typically synchronized to moveat the a matching speed as discussed above. In one embodiment, electrode54 comprises a metal belt that has regions 46 cut out, as shown in theperspective view of FIG. 5 b. Using a method of the invention, polymerpowder granules are injected into the gap between lower electrode 54 andcontact release surface 40 and develop a charge. The charged polymerparticles 36′ will then be driven upwards, concentrating preferentiallyalong lines that are aligned with solid sections 33 of belt electrode 54(i.e. being less concentrated along lines that align with the cutoutholes in electrode 54). The particles thus impinge on release surface 40in a pattern corresponding to that established by the patterned beltelectrode 54. In an alternative embodiment, electrode 53 can also be apatterned moving belt electrode, and can move in tandem with electrode54, so as to achieve further concentration of the particles in thedesired areas of the contact release surface. Further processing of theparticles on base sheet 4 is as described with regard to FIG. 4 a (Inthis instance there is no mask from which particles need be removed.)

The method depicted in FIG. 6 a is a subset method of the invention.Using this method of the invention, polymer powder granules areprovided, as polymer particles 36. A base 4 sheet is fed into the systemfrom a suitable source. The base 4 sheet in this embodiment is providedwith regions 5 (FIG. 6 b) that will preferably bond to the preformprojections and areas 6 that will preferably not bond to the preformprojections (as shown in FIG. 6 b). The contact release surface 40 isprovided on a release conveyor 39 that is driven around two driverollers 11. The contact release surface 40 is kept horizontal. No maskis used.

At the beginning of the operation cycle, the horizontal contact releasesurface 40 is kept at an elevated temperature by a hot plate 24. Thiscould be done under the release conveyor 39, though further hotchambers, on the top side of a release conveyor, could also be utilized.A scatter unit 42 is used to evenly disperse the polymer particles 36onto the release surface 40. The particles are distributed on thecontact release surface 40 to form preform projections 37. Cooling isprovided by a cooling plate 45 at a controlled temperature under thecontact release surface 40 forming cooled preform projections 44. Thecooled preform projections 44 are made solid at least in part. The base4 is laid over the preform projections 44 on the contact release surface40. The front surface 20 of the base 4 contacts the terminal ends of thepreform projections 44. A hot air blowing unit 23 can be fixed above theback surface 3 of the base 4. Hot gas 21 is blown on the back surface 3of the base 4, which could be done while the release conveyor 39 and thebase 4 are together kept in motion in a lateral direction 25. Each pointof the base 4 is exposed to the hot air for a time sufficient to softenand fix the terminal ends of the preform projections 44 to the frontsurface 20 of the base 4. The base is then cooled which could be done byair blower 12. The base 4, together with the engaging projections 13fixed thereto, in the regions 5 that will preferably bond to the preformprojections 44, is separated and removed from the contact releasesurface 40. Unbonded preform projections 44 on nonbonding areas 6 of thebase film 4, or on the contact release surface 40, may be removed suchas by vacuum removal device 49 or by sticky rolls.

The method depicted in FIG. 7 a is a further subset method of theinvention. Using this method of the invention, polymer powder granulesare provided, as polymer particles 36. A base 4 sheet is fed into thesystem from a suitable source. The base 4 sheet in this embodiment ismasked using a transfer masking belt 71 provided with open areas 75 thatwill allow the preform projections to contact the base sheet 4 and solidareas 76 that will not allow preform projections to contact base sheet 4(In this configuration the masking belt 71 should be sufficiently thinthat the preform projections are able to protrude or pushed through theopen areas so as to contact the base sheet.). One such belt is shown nFIG. 7 b. The contact release surface 40 is provided on a releaseconveyor 39 that is driven around two drive rollers 11. The contactrelease surface 40 is kept horizontal.

At the beginning of the operation cycle, the horizontal contact releasesurface 40 is kept at an elevated temperature by a hot plate 24. Thiscould be done under the release conveyor 39, though further hotchambers, on the top side of a release conveyor, could also be utilized.A scatter unit 42 is used to evenly disperse the polymer particles 36onto the release surface 40. The particles are distributed on thecontact release surface 40 to form preform projections 37. Cooling isprovided by a cooling plate 45 at a controlled temperature under thecontact release surface 40 so as to form cooled preform projections 44.The cooled preform projections 44 are made solid and suitable forcontacting with the front surface 20 of the base 4. The base 4 is laidover the preform projections 44 on the contact release surface 40. Thefront surface 20 of the base 4 contacts the terminal ends of the preformprojections 44 through the open areas 75 provided in the transfermasking belt 71. A hot air blowing unit 23 can be fixed above the backsurface 3 of the base 4. Hot gas 21 is blown on the back surface 3 ofthe base 4, which could be done while the release conveyor 39 and thebase 4 are together kept in motion in a lateral direction 25. Each pointof the base 4 is exposed to the hot air for a time sufficient to softenand fix the terminal ends of the preform projections 44 to the frontsurface 20 of the base 4. Then the base is cooled which could be done byair blower 12. The base 4, together with the engaging projections 13fixed thereto in the areas open, through the open areas 75 is separatedand removed from the contact release surface 40, which could then woundup in a reel. Any remaining preform projections 44 on the contactrelease surface or on the transfer masking belt 71 may be removed by aremoval device such as described for FIG. 6 a.

Example Method for Discrete Deposition of Particles on a Base Film

A process was set up similar to that depicted in FIG. 2 a. A contactrelease surface was provided comprising a polytetrafluoroethylene-coatedglass fiber web, with a slightly textured surface, available fromLörincz kft, Hungary, under the designation Chemglas 100-6. The surfaceenergy of the contact release surface 40 was about 18.5 mJ/m². Thecontact release surface was present as a horizontal sheet on the topsurface of a shuttle that could be moved laterally, in order to simulatethe continuous belt conveyor system of FIG. 2 a.

Polypropylene particles of size range of about 200-500 microns diameterwere placed into a gravity-operated scatter unit (a hopper with afeeding wheel and an underlying screen).

At the beginning of the operation cycle, the horizontal contact releasesurface was brought to a temperature of about 170° C. by a heatingelement located underneath the conveyor shuttle. A masking template withdiscrete shape patterns similar to that shown in FIG. 2 b was placed onthe top of the contact release surface 40. The shuttle was movedlaterally at approximately 0.17 meters per second underneath the scatterunit, which was used to disperse the polymer particles on the heatedcontact release surface at an average density of about 16 g/m² in theparticle deposited regions. The particles were heated by the heat of thecontact release surface and thereby softened or melted into a semiliquidstate. Several seconds after the particles were distributed on therelease surface, they formed preform projections. Then the releasesurface was moved over a cooling plate and halted in position so as tocool the contact release surface to a temperature of about 70° C. Thepreform projections were thus made solid and suitable for contactingwith the front surface of a base film.

A base film was provided comprising a polypropylene film with a basisweight of 74 g/m² (available under product designation FL-3054 from 3MCompany, St Paul, Minn.). The base film was laid over the preformprojections on the contact release surface such that the front surfaceof the base contacted the terminal ends of the preform projections. Ahot air blowing unit which was fixed about 15 mm above the back surfaceof the base film, was used to blow air at a measured temperature ofabout 600° C. against the back surface of the base. The shuttle, whichcarried the release contact surface with the preform projections andbase film, was moved laterally at approximately 0.17 meters per secondunderneath the hot air blowing unit. Each point of the base was thusexposed to the hot air, for a short period (typically one second orless), such that the base was softened enough to be fixed with theterminal ends of the preform projections. The terminal ends also meltedfrom the heat to a suitable extent to fuse the preform projections tothe base. The base film with attached projections was then cooled. Thebase, together with the engaging projections fixed thereto, was thenremoved from the contact release surface.

1. A method for forming a fastener comprising: providing a multiplicityof suitable polymer particles; providing a base with a front surface;dispersing onto a contact release surface a multiplicity of polymersparticles in at least one discrete area of the contact release surfaceforming a predetermined shape; providing the polymer particles,dispersed on the contact release surface, in a semiliquid state of asuitable viscosity, at least some of the particles in the discrete areasbeing in contact with the contact release surface for a time sufficientto transform into preform projections; conducting and fixing the frontsurface of the base with the terminal ends of at least some of thepreform projections; removing the base from the contact release surfacethereby separating the preform projections fixed thereto, therebyforming engaging projections projecting from the front surface of thebase in the form of a predetermined shape.